Retarding mixture for alkali-activated binding agents

Abstract

The invention relates to a retarding mixture comprising sodium gluconate and alkali hydrogen carbonate, an alkali-activated binding agent containing sodium gluconate and alkali hydrogen carbonate and a method for adjusting the strength development, wherein sodium gluconate and alkali hydrogen carbonate are added to an alkali-activated binding agent.

1 . Retarding mixture for alakali-activated binding agents, characterised in that it contains a mixture of sodium gluconate and alkali hydrogen carbonate. 
     
     
         2 . Retarding mixture according to  claim 1 , characterised in that the alkali hydrogen carbonate is a sodium hydrogen carbonate, a potassium hydrogen carbonate or a mixture thereof. 
     
     
         3 . Retarding mixture according to  claim 1 , characterised in that the weight ratio of sodium gluconate to alkali hydrogen carbonate ranges from 9:1 to 1:4, preferably from 3:1 to 1:1. 
     
     
         4 . Retarding mixture according to  claim 1 , characterised in that additional retarders based on lignosulphonates, sulphonated naphthalene, melamine or phenol formaldehyde condensates; or based on acrylic acid acrylamide mixtures or polycarboxylate ethers or based on phosphated polycondensates; based on phosphated alkyl carboxylic acids and salts of these; based on (hydroxy)carboxylic acids and carboxylates, in particular citric acid, citrates, tartaric acid, tartrates; borax, boric acid and borates, oxalates; sulfanilic acid; aminocarboxylic acids; salicylic acid and acetylsalicylic acid; dialdehydes and mixtures thereof are contained. 
     
     
         5 . Retarding mixture according to  claim 4 , characterised in that the additional retarders are present in a weight proportion of 10% to 50%, with regard to the retarding mixture. 
     
     
         6 . Retarding mixture according to  claim 4 , characterised in that borax, boric acid and borates are used as additional retarders. 
     
     
         7 . Alkali-activated binding agent comprising latent hydraulic and/or pozzolanic component(s) which provide aluminosilicates and/or silicates and aluminosilicates and/or calcium (alumino)silicates, characterised in that a retarding mixture according to  claim 1  is contained. 
     
     
         8 . Alkali-activated binding agent according to  claim 7 , characterised in that the latent hydraulic and or pozzolanic component(s) are selected from the group consisting of calcined clay, calcium-rich and/or siliceous fly ash, granulated blast furnace slag, slag and mixtures thereof. 
     
     
         9 . Alkali-activated binding agent according to  claim 7 , characterised in that it contains at least 40% latent hydraulic components and/or calcium-rich, pozzolanic components. 
     
     
         10 . Alkali-activated binding agent according to  claim 7 , characterised in that the latent hydraulic and/or pozzolanic component(s) together have a CaO content of at least 10 wt %. 
     
     
         11 . Alkali-activated binding agent according to  claim 7 , characterised in that from 0.1 to 10 wt % retarding mixture with regard to the binding agent, preferably from 0.5 to 5 wt % and most preferably from 1 to 3 wt % are contained. 
     
     
         12 . Alkali-activated binding agent according to  claim 7 , characterised in that the activated is selected from alkali silicates, hydroxides, alkali carbonates, alkali sulphates, Portland cement, Portland cement clinkers and mixtures of two or more thereof. 
     
     
         13 . Alkali-activated binding agent according to  claim 7 , characterised in that the activator has a weight ratio SiO 2 /Na 2 O equivalent  of at least 1.0, preferably of at least 1.25. 
     
     
         14 . Alkali-activated binding agent according to  claim 7 , characterised in that it contains aluminosilicates, silicates and aluminates and/or calcium (alumino)silicates made of calcined clay, calcium-rich and/or siliceous fly ash, granulated blast furnace slag and/or slag. 
     
     
         15 . Alkali-activated binding agent according to  claim 7 , characterised in that concrete liquefier and/or plasticizer and/or additional retarder are contained, preferably based on lignin sulphonates; sulphonated naphthalene, melamine or phenolformaldehyde condensate; or based on acrylic acid acrylamide mixtures or polycarboxylate ethers or based on phosphated polycondensates; phosphated alkyl carboxylic acid and salts of these; (hydroxy)carboxylic acids and carboxylates, in particular citric acid, citrate, tartaric acid, tartrates; borax, boric acid and borates, oxalates; sulfanilic acid; aminocarboxylic acids; salicylic acid and acetylsalicylic acid; dialdehydes and mixtures thereof. 
     
     
         16 . Method for adjusting the strength development of alkali-activated binding agents, characterised in that sodium gluconate and alkali hydrogen carbonate are added to the alkali-activated binding agent as a retarding mixture. 
     
     
         17 . Method according to  claim 16 , characterised in that a sodium hydrogen carbonate, a potassium hydrogen carbonate or a mixture thereof is used as an alkali hydrogen carbonate. 
     
     
         18 . Method according to  claim 16 , characterised in that from 0.1 to 10 wt % of retarders with regard to the binding agent, preferably from 0.5 to 5 wt % and most preferably from 1 to 3 wt %, are used. 
     
     
         19 . Method according to  claim 16 , characterised in that sodium gluconate and alkali hydrogen carbonate are used in a weight ratio sodium gluconate to alkali hydrogen carbonate in the range from 9:1 to 2:8, preferably from about 3:1 to 1:1.